The main goal of this proposal is to develop appropriate comprehensive counseling guidelines for predictive colon cancer gene testing by: (1) assessing perceptions and attitudes toward the gene tests, including their social and psychological determinants, and (2) assessing the impact of the test on at-risk persons. Our specific aims are: 1. To characterize in at-risk individuals those psychosocial factors that predict willingness to undergo genetic testing for colon cancer, to determine projected uses that will be made of the gene test, and to determine the influence of social context, primarily family culture, in shaping at-risk individuals' attitudes toward and perceptions of the gene test. This will be accomplished by a mail survey of 1,000 adults at risk for colon cancer. 2. To compare attitudes toward and perceptions of genetic testing for colon cancer between white and African-American individuals (and a subsample of their families). This will be accomplished with the mail survey data and by qualitative telephone interviews with members of 50 families (25 white, 25 African-American) sampled from the mail survey. 3. To identify predictors of psychological distress associated with pre- and post-disclosure cancer risk perception based on: experiences with cancer, knowledge/beliefs/feelings about cancer, implicit models of illness regarding cancer, cancer risk perceptions, coping behaviors, and tolerance for ambiguity. We will offer MSH2 and MLH1 gene tests to 200 individuals at high risk for colon cancer, based on family history. Data will be collected by questionnaire and interviews before and after gene testing (at one month, six months, and one year post disclosure). The gene test will result in one of three possible outcomes: definite gene- positive, definite gene-negative, and inconclusive gene-negative. The first two outcomes are expected when the mutation in the family is known; the last outcome may occur when the mutation is not known, but the family history is strongly suggestive of hereditary colon cancer. We will stratify on the three outcomes and compare pre- and post disclosure measures of distress and attitudes. 4. To assess post disclosure prevention-oriented health behaviors among persons receiving gene positive, gene negative and inconclusive test results. Because screening recommendations may vary with age, we will stratify our analyses by age groups as well as gene test outcome.